BUG/MEDIUM: ssl: Fix a memory leak in DHE key exchange
OpenSSL does not free the DH * value returned by the callback specified with SSL_CTX_set_tmp_dh_callback(),
leading to a memory leak for SSL/TLS connections using Diffie Hellman Ephemeral key exchange.
This patch fixes the leak by allocating the DH * structs holding the DH parameters once, at configuration time.
Note: this fix must be backported to 1.5.
diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index 375225d..cf8adc7 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -105,6 +105,13 @@
int sslconns = 0;
int totalsslconns = 0;
+#ifndef OPENSSL_NO_DH
+static DH *local_dh_1024 = NULL;
+static DH *local_dh_2048 = NULL;
+static DH *local_dh_4096 = NULL;
+static DH *local_dh_8192 = NULL;
+#endif /* OPENSSL_NO_DH */
+
#ifdef SSL_CTRL_SET_TLSEXT_STATUS_REQ_CB
struct certificate_ocsp {
struct ebmb_node key;
@@ -1034,16 +1041,16 @@
}
if (keylen >= 8192) {
- dh = ssl_get_dh_8192();
+ dh = local_dh_8192;
}
else if (keylen >= 4096) {
- dh = ssl_get_dh_4096();
+ dh = local_dh_4096;
}
else if (keylen >= 2048) {
- dh = ssl_get_dh_2048();
+ dh = local_dh_2048;
}
else {
- dh = ssl_get_dh_1024();
+ dh = local_dh_1024;
}
return dh;
@@ -1079,11 +1086,11 @@
if (global.tune.ssl_default_dh_param <= 1024) {
/* we are limited to DH parameter of 1024 bits anyway */
- dh = ssl_get_dh_1024();
- if (dh == NULL)
+ local_dh_1024 = ssl_get_dh_1024();
+ if (local_dh_1024 == NULL)
goto end;
- SSL_CTX_set_tmp_dh(ctx, dh);
+ SSL_CTX_set_tmp_dh(ctx, local_dh_1024);
}
else {
SSL_CTX_set_tmp_dh_callback(ctx, ssl_get_tmp_dh);
@@ -1593,6 +1600,28 @@
global.tune.ssl_default_dh_param = 1024;
}
+
+#ifndef OPENSSL_NO_DH
+ if (global.tune.ssl_default_dh_param >= 1024) {
+ if (local_dh_1024 == NULL) {
+ local_dh_1024 = ssl_get_dh_1024();
+ }
+ if (global.tune.ssl_default_dh_param >= 2048) {
+ if (local_dh_2048 == NULL) {
+ local_dh_2048 = ssl_get_dh_2048();
+ }
+ if (global.tune.ssl_default_dh_param >= 4096) {
+ if (local_dh_4096 == NULL) {
+ local_dh_4096 = ssl_get_dh_4096();
+ }
+ if (global.tune.ssl_default_dh_param >= 8192 &&
+ local_dh_8192 == NULL) {
+ local_dh_8192 = ssl_get_dh_8192();
+ }
+ }
+ }
+ }
+#endif /* OPENSSL_NO_DH */
SSL_CTX_set_info_callback(ctx, ssl_sock_infocbk);
#if OPENSSL_VERSION_NUMBER >= 0x00907000L